The present invention relates to missile systems and is particularly concerned with a missile system in which a bus missile carrying a plurality of sub-missiles is launched from a launch station remote from a target and the sub-missiles launched from the bus missile during flight of the bus missile.
Efforts are constantly being made to provide naval vessels with defensive systems capable of dealing with anti-ship missiles and particular attention has been directed to defensive systems against missiles which fly at low level and at low supersonic speed. As a consequence of this, a requirement now exists to provide a missile system which can be used effectively against naval vessels equipped with such defensive systems.
It is accordingly one object of the present invention to provide a missile system which has a better prospect of penetrating naval vessel defense systems mounted against it and to a method of missile guidance for this purpose.
It is furthermore another object of the present invention to provide a missile system for use in anti-missile engagements, ranging from engagements against low flying missiles such as cruise and sea-skimming missiles to engagements against long range high trajectory missiles.
According to a first aspect of the present invention there is provided a missile system comprising a bus missile, bus missile guidance means for guiding the bus missile toward a target from a launch station remote from the target, a plurality of sub-missiles carried by the bus missile, sub-missile launch means to launch the sub-missiles from the bus missile during flight of the bus missile whereby they deploy ahead of the bus missile and a sub-missile guidance beam generating means within the bus missile for generating and transmitting a sub-missile guidance beam to guide the sub-missiles to the target.
Preferably, the sub-missiles are guided to the target in a predetermined but variable spatial pattern.
Preferably, the bus missile includes a sustainer motor for sustaining flight of the bus missile to the target and the sustainer motor of the bus missile is such as to bring the missile to and sustain it at a predetermined low supersonic speed.
In a preferred embodiment of the invention hereinafter to be described the bus missile includes a booster motor for accelerating the bus missile during a final acceleration phase when it closes to a predetermined range from the target. Preferably, the booster motor is such as to accelerate the bus missile during the final acceleration phase to a speed of at least twice the mid-course speed.
The sub-missile launch means is preferably operative to launch the sub-missiles at the end of the final acceleration phase.
In an embodiment of the invention hereinafter to be described flight direction control means of the bus missile are made responsive to a predetermined control signal to cause the bus missile to climb to an increased altitude during the final acceleration phase and the sub-missiles are launched at the increased altitude and on a rising trajectory.
In an embodiment of the invention hereinafter to be described the sub-missile guidance beam is a pulsed laser beam providing a scan with respect to a scan axis coincident with the longitudinal axis of the bus vehicle and extending forwardly thereof to provide within an area scanned by the beam a pulse and space modulation sufficient to identify coordinates of any point within the scanned area and each sub-missile includes a receiver for generating control signals for application to flight direction control means of the sub-missile to bring the sub-missile to a selected one of a plurality of spaced sub-missile stations within the scanned area. The sub-missile flight direction control means would normally comprise aerodynamic control surfaces although thrusters may be needed where the missile system is used in space.
In a preferred embodiment of the invention hereinafter to be described, the bus missile comprises a body portion which is caused to rotate during flight, and the sub-missiles are mounted on the body portion of the bus missile. The sub-missiles upon release at launch then deploy radially outwardly from the body portion under centrifugal force.
For a variety of situations, the sub-missile may conveniently take the form of a guided non-power-driven sub-missile. In this event the drag characteristic of each sub-missile relative to the drag characteristic of the bus missile is made such that the sub-missile when launched from the bus missile deploys ahead of the bus missile.
The bus missile guidance means will normally comprise command guidance means located at the bus missile launch station for mid-course flight guidance of the bus missile to the target and in a preferred embodiment of the invention homing guidance means is provided to take up guidance of the bus missile at predetermined range from the target.
In a specific embodiment of the invention hereinafter to be described, the bus missile includes a nose portion rotatable with respect to the body portion and roll attitude control means for controlling the roll attitude of the nose portion during flight of the bus missile. The roll attitude control means is preferably operative to maintain the nose portion roll stabilised in flight.
In the embodiment of the invention hereinafter to be described the sub-missile guidance beam generating means and the homing guidance means are located within the nose portion of the bus missile.
According to a second aspect of the present invention there is provided a method of missile guidance comprising the steps of launching a bus missile from a launch station remote from a target with the bus missile carrying a plurality of sub-missiles, launching the sub-missiles from the bus missile during flight of the bus missile whereby the sub-missiles deploy ahead of the bus missile and guiding the missiles to the target under the control of a guidance beam generated in and transmitted from the bus missile.
Preferably, the sub-missiles are guided to the target in a predetermined but variable spatial pattern.
Preferably, in the method according to the second aspect of the invention, the missile is sustained during mid-course flight at a predetermined low supersonic speed and is accelerated during a final acceleration phase to a speed of at least twice the mid-course speed when it closes to a predetermined range from the target. The sub-missiles are then launched from the bus missile upon completion of the final acceleration phase of the bus missile.
In use, as an anti-ship missile system, for example, the bus vehicle can be launched from an attack ship or other launch platform at extended range from the target to be attacked. The bus vehicle may be vertically or directionally launched according to the means chosen. The bus vehicle is then guided toward the target usually, but not essentially, at low supersonic speed and at low level to avoid detection. It is contemplated that in preferred embodiments, at some predetermined distance from the target which is ideally but not essentially outside the range of ship defence systems capable of engaging the known threat from slow and low-flying missiles, the bus missile is accelerated to a significantly higher speed and a rising flight path. During this trajectory, it releases the sub-missiles which are guided towards the target along a guidance beam generated within and transmitted from the bus vehicle. The salvo of small sub-missiles is then directed in a pre-arranged pattern along the beam toward the target, presenting a very difficult defence problem.
The missile system as hereinafter to be described with reference to the drawings may with particular advantage be used in anti-ship engagements, with the bus missile being launched from another naval vessel. It will however be appreciated that the missile system and the method of missile guidance according to the invention may also be used in other combat situations.
Clearly, the missile system according to the invention may be used in surface-to-air and air-to-air engagements. It may with advantage be used in anti-missile engagements, for example against low flying missiles, such as cruise or sea skimming missiles or against long range high trajectory missiles.
In air-to-ground engagements, for example, the bus missile could be launched by an attacking aircraft and initially guided to the target under command guidance control. Once the bus missile comes under homing control the aircraft is free to take evasive action and to attack other targets. The missile system according to the invention could be utilised for combat in space, although clearly rocket thrusters would be needed for guidance of the bus missile and the sub-missiles launched from it.